Random-play control system in disk player

ABSTRACT

In a disk player, upon the lock-in of the focus servo at the turn-on of the main power source, the information recorded on an information recording disk is read and the sub-code information such as frame numbers, time code, or the like which are obtained from the read output are set to fundamental information for generation of random numbers in the random play mode, so that the initial value for the random numbers is set at random. The programs can be played in accordance with the different sequences even for the same disk. A preferable random-play control can be performed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a random-play control system in a diskplayer.

2. Description of the Related Background Art

There is known a random-play control system in a disk player for playingat random a plurality of pieces of information such as music piecesrecorded on an information recording disk (hereinafter, simply referredto as a disk) while setting a play sequence for those music pieces whichare designated at random by using random numbers.

When a digital audio disk player is mounted on a motor vehicle andperforms such a random-play control system, the control system is madeoperative by the main power source which is driven through the so-calledaccessory (hereinafter, abbreviated to AOC) switch of the motor vehicle.With this arrangement, a random number generator is initialized at everytime when the ACC is turned on. On the other hand, the random numbergenerator starts in response to a random play command. Therefore, therandom number generator produces random numbers in the same sequence sothat the music pieces are played in the same sequence for the same diskat the first random-play cycle upon the random-play command.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a random-playcontrol system in a disk player in which the initial values of therandom numbers are always set to different values, thereby avoiding suchphenomenon that the programs on the same disk are always played in thesame sequence at the initial step of the random-play.

The random-play control system in a disk player according to the presentinvention reads the information recorded on the information recordingdisk upon the lock-in of the focus servo and derives the so-calledsub-code signal from the read signal so as to use it as the initialvalue for generation of the random numbers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an example of an arrangement of, forexample, an auto-loading disk player which is provided with arandom-play control system according to the present invention; and

FIG. 2 is a flowchart showing a procedure of the random-play controlsystem according to the present invention, which procedure is executedby a processor.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

In FIG. 1, a controller 1 consists of a microcomputer including a memory(not shown) such as an RAM. On the basis of various kinds of commandsignals which are generated from a manual operation unit 2 and variouskinds of detection signals which are produced from detecting switches 3ato 3c, the controller 1 controls a loading mechanism 5 a slider servocircuit 6, a focus servo circuit 7, a tracking servo circuit 8, and soon at predetermined timings. The switch 3a is a disk insertion detectingswitch to detect that a disk D has been inserted from a slot (not shown)formed in the front panel of the player main body. The disk D carriesthereon not only a plurality of information signals each representing aninformation piece such as a music piece but also the so-called sub-codesignals. The disk D may be the so-called CD, CDV or LD which carries theinformation signals and the sub-code signals recorded under apredetermined format. In that case the sub-code signals are theso-called frame number signal, the so-called time code signal, etc. Theswitch 3b is a disk loading detecting switch to detect that the disk Dhas been conveyed to the play position by the loading mechanism 5. Theswitch 3c is a disk carry-out detecting switch to detect that the disk Dhas been carried out to the ejecting position by the loading mechanism.The controller I and other mechanisms are activated by the main powersource which is activated by a voltage supplied through the accessory(ACC) switch of the motor vehicle.

The disk D is rotated by a spindle motor 9 and an information signalrecorded on the disk D is read by an optical pickup 10. The pickup 10includes: an optical system including a laser diode, an objective lens,a photodetector, and the like; a focus actuator to drive the objectivelens in its optical axis direction with respect to the informationrecording surface of the disk D; and a tracking actuator to deviate abeam spot (information reading spot) which is generated from the pickup10 in the radial direction of the disk for making the beam spot to tracethe recording track. The focus actuator is controlled by the focus servocircuit 7. The tracking actuator is controlled by the tracking servocircuit 8. The pickup 10 is mounted on a slider (not shown) which ismovable in the radial direction of the disk and is driven by a slidermotor 11.

The read information signal which is produced from the pickup 10 in theform of an RF signal is supplied through an RF amplifier 12 to ademodulation and correction circuit 13 which demodulates the RF signaland performs the error correction operation. The output signal of thedemodulation and correction circuit 13 is properly processed by a signalprocessor 14, so that audio output signals in the right and leftchannels are obtained. On the other hand, the output of the circuit 13is directly supplied to a data extracting circuit 15 extracts the TOO(table of contents) data which is read out from the lead-in area beforethe start of the play operation and includes the sub-code signals whichare also obtained from the read signal during the play operation. Theextracted data are respectively supplied to the controller 1.

The controller 1 stores the TOC data supplied from the data extractingcircuit 15, the data indicative of the play sequence designated throughthe manual operation unit 2, into the memory. Then, the controller 1performs the control operation for loading ejecting the disk by means ofthe loading mechanism 5. The controller 1 operates to open or close theservo loops of the focus servo circuit 7 and tracking servo circuit 8.The controller 1 performs a normal play control for sequentially playinga plurality of music pieces recorded on the disk in accordance with therecorded order and a programmed play control for playing the musicpieces in accordance with the sequence which has previously been storedin the memory. When the controller 1 receives a lock-in signal from thefocus servo circuit 7 at an initial stage after the turn-on of the mainpower source, the controller 1 reads a sub-code signal derived from theread signal and supplies it to the random number generator 16 as aninitial value for generation of the random numbers in the random numbergenerator 16. When the controller 1 receives the random play modecommand from the manual operation unit 2, the controller 1 controls theslider servo circuit 6 and the tracking servo circuit 8 so as to searchsome of the music pieces which are sequentially designated by the outputdata from the random number generator 16. The generator 16 may be soarranged as to latch a count value issued from n (n is a natural number)notation counter whose count value sequentially changes at a very shortperiod in response to a random number issue command from the controller1 and issues the latched count value ad its output random number untilthe next random number issue command.

A routine for the random-play control system according to the presentinvention which is executed by a processor contained in the controller 1will now be described with reference to a flowchart of FIG. 2. Thisroutine is accessed when the main power source is turned on.

When it is detected that the power source is turned on (step S1), theprocessor first cancels the reset of the microcomputer (step S2). Then,the processor checks whether the disk has been still remained at theplay position or not (step S3). If the presence of the disk has beendetected, the servo loop is closed by the lock-in signal from the focusservo circuit 7 and makes the tracking servo loop to be subsequentlyclosed (step S4). Thereafter, the sub-code signal is entered which isobtained from the data extract circuit 15 (step S5). For example, aframe number datum or a time code datum in the sub-code data is set asan initial value for generation of the random numbers in the randomnumber generator 16 (step S6).

If, in the next step S7, it is determined that the random play mode hasbeen instructed by the key operation in the manual operation unit 2, therandom number issue command is sent to the random number generator 16which then sequentially produces the random number data by using theframe number datum or the time code datum as the initial value (stepS8). The order of the music pieces which are played at random isdetermined on the basis of the random number data (step S9). The leadingposition of the music pieces determined are searched (step S10).Thereafter, the sub-routine to control the play mode is accessed and theplay mode routine is executed (step S11). After execution of thesub-routine, the processor restarts the execution of the main routine.If it is determined in step S7 that the random play mode is notdesignated, the normal play mode is executed in the step S11.

In this manner, after the focus servo has been locked in at the turn-onof the main power source, the information recorded on the disk is readand the sub-code data obtained from the read signal is set to theinitial values of the random numbers, so that the initial values of therandom numbers may be set to different values even for the same diskupon the repeated switchings of the accessory switch. That is, it isprevented that the music pieces or programs are performed in accordancewith the same sequence each time when the main power source is turnedon. The programs can be performed in accordance with the differentsequences every time when the main power source is turned on. Adesirable random play can be made.

As described above, according to the random play system according to thepresent invention, the information recorded on the disk is read and thesub-code information obtained from the read output is used as basicinformation for generation of random numbers, so that the initial valuesof the random numbers may be always set to the different values.Consequently, it is prevented that of the programs of the same disk, theprograms are always played for the same disk in accordance with the samesequence. The programs can be played in accordance with the differentsequences every turn-on of the main power source.

What is claimed is:
 1. A random-play control system in a disk player forplaying a disk containing sub-code signals which identify a plurality ofprograms, said random-play control system comprising:(a) a sub-codeextractor for extracting said sub-code signals upon turn-on of a powersource for the disk player; (b) a random number generator for generatingrandom number data by starting from an initial number obtained from oneof the extracted sub-code signals independently of said random numbergenerator; and (c) determining means for determining one or moreprograms to be played in accordance with one or more random numbers ofsaid random number data.
 2. A system according to claim 1, wherein saidnumber contained in the extracted sub-code signals is a frame number. 3.A system according to claim 1, wherein said number contained in theextracted sub-code signals is a time code.